1. Field of the Invention
This invention relates to a temporary closure for use with an opening in containers such as storage tanks or the like. In particular, the temporary closure can be placed in a tank opening in a longitudinal direction but cannot be easily removed unless it is rotated relative to the tank opening.
2. Description of the Prior Art
Temporary closures for storage tanks are known. Unfortunately, previous temporary closures do not tightly close the tank opening; or, they can be pulled entirely into the tank or forced outwardly from the opening by pressure changes within the tank; or, they are cumbersome to install or remove; or, they do not permit the passage of air into or out of the tank; or, they do not prevent the entry of free-falling water into the tank; or, they are too complex or too expensive to manufacture.